网上流行的学生选课相关的50个常用sql语句
学生表 Student(S#,Sname,Sage,Ssex)
教师表 Teacher(T#,Tname)
课程表 Course(C#,Cname,T#)
学生成绩表 SC(S#,C#,score)
问题：
1、查询“001”课程比“002”课程成绩高的所有学生的学号;
SELECT a.s# FROM ( SELECT * FROM dbo.SC WHERE c# = '001' ) a INNER JOIN ( SELECT * FROM dbo.SC WHERE c# = '002' ) b ON a.s# = b.s# WHERE a.score > b.score
2、查询平均成绩大于60分的同学的学号和平均成绩;
SELECT s# , AVG(score) FROM dbo.SC GROUP BY s# HAVING AVG(score) > 60
3、查询所有同学的学号、姓名、选课数、总成绩;
SELECT a.s# , a.sname , COUNT(b.c#) , SUM(b.score) FROM dbo.Student a LEFT OUTER JOIN dbo.SC b ON a.s# = b.s# GROUP BY a.s# , a.sname
4、查询姓“李”的老师的个数;
SELECT COUNT(DISTINCT tname) FROM dbo.Teacher WHERE tname LIKE '李%'
5、查询没学过“叶平”老师课的同学的学号、姓名;
SELECT Student.S# , Student.Sname FROM Student WHERE S# NOT IN ( SELECT DISTINCT ( SC.S# ) FROM SC , Course , Teacher WHERE SC.C# = Course.C# AND Teacher.T# = Course.T# AND Teacher.Tname = '叶平' )
6、查询学过“001”并且也学过编号“002”课程的同学的学号、姓名;
SELECT Student.S# , Student.Sname FROM Student , SC WHERE Student.S# = SC.S# AND SC.C# = '001' AND EXISTS ( SELECT * FROM SC AS SC_2 WHERE SC_2.S# = SC.S# AND SC_2.C# = '002' )
7、查询学过“叶平”老师所教的所有课的同学的学号、姓名;
SELECT S# , Sname FROM Student WHERE S# IN ( SELECT S# FROM SC , Course , Teacher WHERE SC.C# = Course.C# AND Teacher.T# = Course.T# AND Teacher.Tname = '叶平' GROUP BY S# HAVING COUNT(SC.C#) = ( SELECT COUNT(C#) FROM Course , Teacher WHERE Teacher.T# = Course.T# AND Tname = '叶平' ) )
8、查询课程编号“002”的成绩比课程编号“001”课程低的所有同学的学号、姓名;
SELECT S# , Sname FROM ( SELECT Student.S# , Student.Sname , score , ( SELECT score FROM SC SC_2 WHERE SC_2.S# = Student.S# AND SC_2.C# = '002' ) score2 FROM Student , SC WHERE Student.S# = SC.S# AND C# = '001' ) S_2 WHERE score2 < score
9、查询所有课程成绩小于60分的同学的学号、姓名;
SELECT S# , Sname FROM Student WHERE S# NOT IN ( SELECT Student.S# FROM Student , SC WHERE Student.S# = SC.S# AND score > 60 )
10、查询没有学全所有课的同学的学号、姓名;
SELECT Student.S# , Student.Sname FROM Student , SC WHERE Student.S# = SC.S# GROUP BY Student.S# , Student.Sname HAVING COUNT(C#) < ( SELECT COUNT(C#) FROM Course )
11、查询至少有一门课与学号为“1001”的同学所学相同的同学的学号和姓名;
SELECT S# , Sname FROM Student , SC WHERE Student.S# = SC.S# AND C# IN ( SELECT C# FROM SC WHERE S# = '1001' )
12、查询至少学过学号为“001”同学所有一门课的其他同学学号和姓名;
SELECT DISTINCT SC.S# , Sname FROM Student , SC WHERE Student.S# = SC.S# AND C# IN ( SELECT C# FROM SC WHERE S# = '001' )
13、把“SC”表中“叶平”老师教的课的成绩都更改为此课程的平均成绩;
UPDATE SC SET score = ( SELECT AVG(SC_2.score) FROM SC SC_2 WHERE SC_2.C# = SC.C# ) FROM Course , Teacher WHERE Course.C# = SC.C# AND Course.T# = Teacher.T# AND Teacher.Tname = '叶平'
14、查询和“1002”号的同学学习的课程完全相同的其他同学学号和姓名;
SELECT S# FROM SC WHERE C# IN ( SELECT C# FROM SC WHERE S# = '1002' ) GROUP BY S# HAVING COUNT(*) = ( SELECT COUNT(*) FROM SC WHERE S# = '1002' )
15、删除学习“叶平”老师课的SC表记录;
DELETE SC FROM course , Teacher WHERE Course.C# = SC.C# AND Course.T# = Teacher.T# AND Tname = '叶平'
16、向SC表中插入一些记录，这些记录要求符合以下条件：没有上过编号“003”课程的同学学号、2、 号课的平均成绩;
INSERT SC SELECT S# , '002' , ( SELECT AVG(score) FROM SC WHERE C# = '002' ) FROM Student WHERE S# NOT IN ( SELECT S# FROM SC WHERE C# = '002' )
17、按平均成绩从高到低显示所有学生的“数据库”、“企业管理”、“英语”三门的课程成绩，按如下形式显示： 学生ID,,数据库,企业管理,英语,有效课程数,有效平均分
SELECT S# AS 学生ID , ( SELECT score FROM SC WHERE SC.S# = t.S# AND C# = '004' ) AS 数据库 , ( SELECT score FROM SC WHERE SC.S# = t.S# AND C# = '001' ) AS 企业管理 , ( SELECT score FROM SC WHERE SC.S# = t.S# AND C# = '006' ) AS 英语 , COUNT(*) AS 有效课程数 , AVG(t.score) AS 平均成绩 FROM SC AS t GROUP BY S# ORDER BY AVG(t.score)
18、查询各科成绩最高和最低的分：以如下形式显示：课程ID，最高分，最低分
SELECT L.C# AS 课程ID , L.score AS 最高分 , R.score AS 最低分 FROM SC L , SC AS R WHERE L.C# = R.C# AND L.score = ( SELECT MAX(IL.score) FROM SC AS IL , Student AS IM WHERE L.C# = IL.C# AND IM.S# = IL.S# GROUP BY IL.C# ) AND R.Score = ( SELECT MIN(IR.score) FROM SC AS IR WHERE R.C# = IR.C# GROUP BY IR.C# )
19、按各科平均成绩从低到高和及格率的百分数从高到低顺序
SELECT t.C# AS 课程号 , MAX(course.Cname) AS 课程名 , ISNULL(AVG(score), 0) AS 平均成绩 , 100 * SUM(CASE WHEN ISNULL(score, 0) >= 60 THEN 1 ELSE 0 END) / COUNT(*) AS 及格百分数 FROM SC T , Course WHERE t.C# = course.C# GROUP BY t.C# ORDER BY 100 * SUM(CASE WHEN ISNULL(score, 0) >= 60 THEN 1 ELSE 0 END) / COUNT(*) DESC
20、查询如下课程平均成绩和及格率的百分数(用"1行"显示): 企业管理（001），马克思（002），OO&UML （003），数据库（004）
SELECT SUM(CASE WHEN C# ='001' THEN score ELSE 0 END)/SUM(CASE C# WHEN '001' THEN 1 ELSE 0 END) AS 企业管理平均分 ,100 * SUM(CASE WHEN C# = '001' AND score >= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN C# = '001' THEN 1 ELSE 0 END) AS 企业管理及格百分数 ,SUM(CASE WHEN C# = '002' THEN score ELSE 0 END)/SUM(CASE C# WHEN '002' THEN 1 ELSE 0 END) AS 马克思平均分 ,100 * SUM(CASE WHEN C# = '002' AND score >= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN C# = '002' THEN 1 ELSE 0 END) AS 马克思及格百分数 ,SUM(CASE WHEN C# = '003' THEN score ELSE 0 END)/SUM(CASE C# WHEN '003' THEN 1 ELSE 0 END) AS UML平均分 ,100 * SUM(CASE WHEN C# = '003' AND score >= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN C# = '003' THEN 1 ELSE 0 END) AS UML及格百分数 ,SUM(CASE WHEN C# = '004' THEN score ELSE 0 END)/SUM(CASE C# WHEN '004' THEN 1 ELSE 0 END) AS 数据库平均分 ,100 * SUM(CASE WHEN C# = '004' AND score >= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN C# = '004' THEN 1 ELSE 0 END) AS 数据库及格百分数 FROM SC
21、查询不同老师所教不同课程平均分从高到低显示
SELECT max(Z.T#) AS 教师ID,MAX(Z.Tname) AS 教师姓名,C.C# AS 课程ＩＤ,MAX(C.Cname) AS 课程名称,AVG(Score) AS 平均成绩 FROM SC AS T,Course AS C ,Teacher AS Z where T.C#=C.C# and C.T#=Z.T# GROUP BY C.C# ORDER BY AVG(Score) DESC
22、查询如下课程成绩第 3 名到第 6 名的学生成绩单：企业管理（001），马克思（002），UML （003），数据库（004） [学生ID],[学生姓名],企业管理,马克思,UML,数据库,平均成绩
SELECT DISTINCT top 3 SC.S# As 学生学号, Student.Sname AS 学生姓名 , T1.score AS 企业管理, T2.score AS 马克思, T3.score AS UML, T4.score AS 数据库, ISNULL(T1.score,0) + ISNULL(T2.score,0) + ISNULL(T3.score,0) + ISNULL(T4.score,0) as 总分 FROM Student,SC LEFT JOIN SC AS T1 ON SC.S# = T1.S# AND T1.C# = '001' LEFT JOIN SC AS T2 ON SC.S# = T2.S# AND T2.C# = '002' LEFT JOIN SC AS T3 ON SC.S# = T3.S# AND T3.C# = '003' LEFT JOIN SC AS T4 ON SC.S# = T4.S# AND T4.C# = '004' WHERE student.S#=SC.S# and ISNULL(T1.score,0) + ISNULL(T2.score,0) + ISNULL(T3.score,0) + ISNULL(T4.score,0) NOT IN (SELECT DISTINCT TOP 15 WITH TIES ISNULL(T1.score,0) + ISNULL(T2.score,0) + ISNULL(T3.score,0) + ISNULL(T4.score,0) FROM sc LEFT JOIN sc AS T1 ON sc.S# = T1.S# AND T1.C# = 'k1' LEFT JOIN sc AS T2 ON sc.S# = T2.S# AND T2.C# = 'k2' LEFT JOIN sc AS T3 ON sc.S# = T3.S# AND T3.C# = 'k3' LEFT JOIN sc AS T4 ON sc.S# = T4.S# AND T4.C# = 'k4' ORDER BY ISNULL(T1.score,0) + ISNULL(T2.score,0) + ISNULL(T3.score,0) + ISNULL(T4.score,0) DESC)
23、统计列印各科成绩,各分数段人数:课程ID,课程名称,[100-85],[85-70],[70-60],[ <60]
SELECT SC.C# as 课程ID, Cname as 课程名称 ,SUM(CASE WHEN score BETWEEN 85 AND 100 THEN 1 ELSE 0 END) AS [100 - 85] ,SUM(CASE WHEN score BETWEEN 70 AND 85 THEN 1 ELSE 0 END) AS [85 - 70] ,SUM(CASE WHEN score BETWEEN 60 AND 70 THEN 1 ELSE 0 END) AS [70 - 60] ,SUM(CASE WHEN score < 60 THEN 1 ELSE 0 END) AS [60 -] FROM SC,Course where SC.C#=Course.C# GROUP BY SC.C#,Cname
24、查询学生平均成绩及其名次
SELECT 1+(SELECT COUNT( distinct 平均成绩) FROM (SELECT S#,AVG(score) AS 平均成绩 FROM SC GROUP BY S# ) AS T1 WHERE 平均成绩 > T2.平均成绩) as 名次, S# as 学生学号,平均成绩 FROM (SELECT S#,AVG(score) 平均成绩 FROM SC GROUP BY S# ) AS T2 ORDER BY 平均成绩 desc
25、查询各科成绩前三名的记录:(不考虑成绩并列情况)
SELECT t1.S# as 学生ID,t1.C# as 课程ID,Score as 分数 FROM SC t1 WHERE score IN (SELECT TOP 3 score FROM SC WHERE t1.C#= C# ORDER BY score DESC ) ORDER BY t1.C#;
26、查询每门课程被选修的学生数
select c#,count(S#) from sc group by C#;
27、查询出只选修了一门课程的全部学生的学号和姓名
select SC.S#,Student.Sname,count(C#) AS 选课数 from SC ,Student where SC.S#=Student.S# group by SC.S# ,Student.Sname having count(C#)=1;
28、查询男生、女生人数
Select count(Ssex) as 男生人数 from Student group by Ssex having Ssex='男'; Select count(Ssex) as 女生人数 from Student group by Ssex having Ssex='女';
29、查询姓“张”的学生名单
SELECT Sname FROM Student WHERE Sname like '张%';
30、查询同名同性学生名单，并统计同名人数
select Sname,count(*) from Student group by Sname having count(*)>1;;
31、1981年出生的学生名单(注：Student表中Sage列的类型是datetime)
select Sname, CONVERT(char (11),DATEPART(year,Sage)) as age from student where CONVERT(char(11),DATEPART(year,Sage))='1981';
32、查询每门课程的平均成绩，结果按平均成绩升序排列，平均成绩相同时，按课程号降序排列
Select C#,Avg(score) from SC group by C# order by Avg(score),C# DESC ;
33、查询平均成绩大于85的所有学生的学号、姓名和平均成绩
select Sname,SC.S# ,avg(score) from Student,SC where Student.S#=SC.S# group by SC.S#,Sname having avg(score)>85;
34、查询课程名称为“数据库”，且分数低于60的学生姓名和分数
Select Sname,isnull(score,0) from Student,SC,Course where SC.S#=Student.S# and SC.C#=Course.C# and Course.Cname='数据库'and score <60;
35、查询所有学生的选课情况;
SELECT SC.S#,SC.C#,Sname,Cname FROM SC,Student,Course where SC.S#=Student.S# and SC.C#=Course.C# ;
36、查询任何一门课程成绩在70分以上的姓名、课程名称和分数;
SELECT distinct student.S#,student.Sname,SC.C#,SC.score FROM student,Sc WHERE SC.score>=70 AND SC.S#=student.S#;
37、查询不及格的课程，并按课程号从大到小排列
select c# from sc where score <60 order by C# ;
38、查询课程编号为003且课程成绩在80分以上的学生的学号和姓名;
select SC.S#,Student.Sname from SC,Student where SC.S#=Student.S# and Score>80 and C#='003';
39、求选了课程的学生人数
select count(*) from sc;
40、查询选修“叶平”老师所授课程的学生中，成绩最高的学生姓名及其成绩
select Student.Sname,score from Student,SC,Course C,Teacher where Student.S#=SC.S# and SC.C#=C.C# and C.T#=Teacher.T# and Teacher.Tname='叶平' and SC.score=(select max(score)from SC where C#=C.C# );
41、查询各个课程及相应的选修人数
select c#,count(*) from sc group by C#;
42、查询不同课程成绩相同的学生的学号、课程号、学生成绩
select distinct A.S#,B.score from SC A ,SC B where A.Score=B.Score and A.C# <>B.C# ;
43、查询每门功成绩最好的前两名
SELECT t1.S# as 学生ID,t1.C# as 课程ID,Score as 分数 FROM SC t1 WHERE score IN (SELECT TOP 2 score FROM SC WHERE t1.C#= C# ORDER BY score DESC )
ORDER BY t1.C#;
44、统计每门课程的学生选修人数（超过10人的课程才统计）。要求输出课程号和选修人数，查询结果按人数降序排列，查询结果按人数降序排列，若人数相同，按课程号升序排列
select C# as 课程号,count(*) as 人数 from sc group by C# order by count(*) desc,c#
45、检索至少选修两门课程的学生学号
select S# from sc group by s# having count(*) > = 2
46、查询全部学生都选修的课程的课程号和课程名
select C#,Cname from Course where C# in (select c# from sc group by c#)
47、查询没学过“叶平”老师讲授的任一门课程的学生姓名
select Sname from Student where S# not in (select S# from Course,Teacher,SC where Course.T#=Teacher.T# and SC.C#=course.C# and Tname='叶平');
48、查询两门以上不及格课程的同学的学号及其平均成绩
select S#,avg(isnull(score,0)) from SC where S# in (select S# from SC where score <60 group by S# having count(*)>2)group by S#;
49、检索“004”课程分数小于60，按分数降序排列的同学学号
select S# from SC where C#='004'and score <60 order by score desc;
50、删除“002”同学的“001”课程的成绩
delete from Sc where S#='001'and C#='001';
